President Obama is promoting the decision to end the U.S. combat mission in Iraq on Tuesday as a fulfillment of his campaign promise to draw the war to a close. But some of the president's detractors are using the same moment to question the wisdom of doing so - noting that Iraq is still afflicted with violence and has yet to form a government.

Obama will mark the occasion by flying to Fort Bliss, Tex., to meet with veterans. He will also deliver a prime-time Oval Office speech - only his second since taking office. On Monday, the president visited Walter Reed Army Medical Center and awarded 11 Purple Hearts to combat veterans. Vice President Biden traveled to Iraq to amplify the message.

"Maybe he's entitled to the partial victory lap, but this is not the right moment for it," said analyst Michael O'Hanlon of the Brookings Institution, who has been critical of both Democratic and Republican approaches to the war. "If I were him, I'd wait until we have an Iraqi government, and do it with the Iraqis together."

O'Hanlon said he was "confused about the planned Oval Office speech." It could raise unrealistic expectations among the public about the chances for calm in Iraq, he said. And the timing of the pullout of combat troops may be seen as having more to do with the president's political needs than with real signs of progress on the ground.

White House officials said the speech, scheduled to begin at 8 p.m. and last 15 to 20 minutes, would acknowledge this week's deadline as a "milestone" and pay tribute to the 1.5 million Americans who have served in Iraq since 2003. Obama will address shifting U.S. options now that the country is no longer technically at war in Iraq, including a greater emphasis on Afghanistan and Pakistan.

The president will say that "it's time for Iraq to step up and take responsibility for security in the country," one senior administration official said.

Obama will call former president George W. Bush before the speech, White House press secretary Robert Gibbs said. He did not say whether Obama will give his predecessor credit for the 2007 troop "surge" as Republicans have demanded.

House Minority Leader John A. Boehner, in an opinion piece last week, assailed Obama for taking credit for the drawdown. "While the administration continues seeking credit for 'ending the combat mission' in Iraq, it is important to remember that this transition was made possible by the very surge that President Obama and Vice President Biden opposed," Boehner wrote.

Obama's celebration of an arbitrary deadline - much like Bush's premature "Mission Accomplished" declaration in 2003 - could come back to haunt him if U.S. troops continue to die and the Iraqi government remains unformed.

"If the war is 'over,' what happens if a Black Hawk goes down next week, God forbid?" asked Paul Rieckhoff, a veterans advocate. While combat troops have departed, the tens of thousands of troops still in Iraq are expected to engage in defensive military action when necessary, and Special Forces troops will continue to conduct counterterrorism missions.

"It looks as if al-Qaeda in Iraq is targeting the Iraqi security forces rather than us, and in fact their statements have made it pretty clear that's their objective - trying to show that the Iraqi security forces can't provide the most basic services of government," said L. Paul Bremer, who was the U.S. government's civilian administrator in Iraq in 2003 and 2004. The Obama administration has acknowledged that "there will be some combat," he said.

Bremer believes the bigger threat may come in 2011, when Obama has promised to remove the approximately 50,000 troops who remain.

"The political risk is that in a year it becomes clearer that the Iraqi security forces aren't ready to handle it on their own and ask us to stay on in some form," Bremer said. "There's a risk if [Obama] is too unambiguous about the possiblity of troops staying on."

Obama has been resolute in his pledge to withdraw all troops by the end of 2011, as arranged for by the Status of Forces Agreement signed by Bush. "By the end of next year, all of our troops will be home," the president said in his most recent weekly address.

"We committed to the Iraqis to be out of Iraq's cities last summer on a deadline, and we were," Biden's national security adviser Tony Blinken told reporters in Baghdad. "We committed to change the mission, end our combat mission and be down to 50,000 troops by August 31st, and we are. And we have an agreement with the government of Iraq to remove our forces, all of our forces from Iraq, at the end of 2011, and we will. We are bound by that agreement and we will make good on it."

Some outside observers questioned the decision to stick so firmly to the 2011 deadline - and to describe the current moment as a watershed, given how slowly and unevenly Iraq has improved.

"I don't think moments of transformation are the right way of thinking about Iraq," said Stephen Biddle of the Council on Foreign Relations. "Everybody wants them. Both political leaders and analysts are looking for them as a way of organizing our thoughts about a long, complicated process. But the reality of the situation is Iraq had become an extremely violent ethnic conflict by mid-2006, not unlike the Balkans or Rwanda."

Obama has given just one other Oval Office speech, on the BP oil spill; that he is speaking about Iraq there, rather than from a military base or the Rose Garden, illustrates the significance the White House attaches to the issue.

While he has aggravated liberals in other national security arenas, including his failure to close the prison facility at Guantanamo Bay, Cuba, and his escalation of the war in Afghanistan, Iraq is one relatively bright spot.

"The president and this administration are making good on our commitment to end the war in Iraq responsibly and to help build a stable, self-reliant and sovereign Iraq," Blinken said. Biden, who made his his sixth trip to Iraq to participate in the "change of mission" ceremony, planned to give Iraqi leaders a preview of the president's speech, he said.

Ending combat in Iraq may help offset some concerns about Afghanistan, officials said. Even after deploying an additional 30,000 troops there - taking the total to nearly 100,000 - the reduction in Iraq means that about 30,000 fewer troops are serving "in harm's way" abroad, one administration official said. And the reduction frees up financial resources, including domestic funding for roads, bridges and schools - a point Obama will underscore.

An official said that the president will describe the "kind of expenses we've been making in Iraq versus the kind of investments we will be making here at home."

Scott Wilson contributed to this report.

President Obama is promoting the decision to end the U.S. combat mission in Iraq on Tuesday as a fulfillment of his campaign promise to draw the war to a close. But some of the president's detractors are using the same moment to question the wisdom of doing so - noting that Iraq is still afflicted with violence and has yet to form a government.

Obama will mark the occasion by flying to Fort Bliss, Tex., to meet with veterans. He will also deliver a prime-time Oval Office speech - only his second since taking office. On Monday, the president visited Walter Reed hospital and awarded 11 purple hearts to combat veterans. Vice President Joe Biden traveled to Iraq to further amplify the message.

"Maybe he's entitled to the partial victory lap, but this is not the right moment for it," said analyst Michael O'Hanlon of the Brookings Institution, who has been critical of both Democratic and Republican approaches to the war. "If were him, I'd wait until we have an Iraqi government, and do it with the Iraqis together."

O'Hanlon said he was "confused about the planned Oval Office speech." It could raise unrealistic expectations among the public about the chances for calm in Iraq, he said. And the timing of the pullout may be seen as having more to do with the president's political needs than with real signs of progress on the ground.

White House officials said the speech, scheduled to begin at 8 p.m. and last 15 to 20 minutes, would acknowledge this week's deadline as a "milestone" and pay tribute to the 1.5 million Americans who have served in Iraq since 2003. Obama will address shifting U.S. options now that the country is no longer technically at war in Iraq, including a greater emphasis on Afghanistan and Pakistan - and the domestic economy.

Obama will say that "it's time for Iraq to step up and take responsibility for security in the country," one senior administration official said, and that "it's time to rebalance our resources when it comes to national security and our economy."

Obama will call former President George W. Bush before the speech, White House press secretary Robert Gibbs said. He did not say whether Obama will give his predecessor credit for the surge as Republicans have demanded.

House Minority Leader John Boehner, in an opinion piece last week, assailed Obama for taking credit for the withdrawal. "While the administration continues seeking credit for 'ending the combat mission' in Iraq, it is important to remember that this transition was made possible by the very surge that President Obama and Vice President Biden opposed," Boehner wrote.

Obama's celebration of an arbitrary deadline--much like Bush's premature "Mission Accomplished" declaration in 2003 - could come back to haunt him if U.S. troops continue to die and the Iraqi government remains unformed.

"If the war is 'over,' what happens if a Black Hawk goes down next week, God forbid?" asked Paul Rieckhoff, a veterans advocate. While combat troops have departed, the tens of thousands of troops still in Iraq are expected to engage in defensive military action when necessary, and Special Forces troops will continue to conduct counterterrorism missions.

"It looks as if Al Qaeda in Iraq is targeting the Iraqi security forces rather than us, and in fact their statements have made it pretty clear that's their objective - trying to show that the Iraqi security forces can't provide the most basic services of government," said L. Paul Bremer III, who was the U.S. government's civilian administrator in Iraq in 2003 and 2004. The Obama administration has acknowledged "there will be some combat," he said.

Bremer believes the bigger threat may come in 2011, when Obama has promised to remove the approximately 50,000 troops who remain.

"The political risk is that in a year it becomes clearer that the Iraqi security forces aren't ready to handle it on their own and ask us to stay on in some form," Bremer said. "There's a risk if he [Obama] is too unambiguous about the possiblity of troops staying on."

Obama has been resolute in his pledge to withdraw all troops by the end of 2011, as arranged for by the Status of Forces Agreement signed by President Bush. "By the end of next year, all of our troops will be home," the president said in his most recent weekly address.

"We committed to the Iraqis to be out of Iraq's cities last summer on a deadline, and we were," Biden's national security adviser Tony Blinken told reporters in Baghdad. "We committed to change the mission, end our combat mission and be down to 50,000 troops by August 31st, and we are. And we have an agreement with the government of Iraq to remove our forces, all of our forces from Iraq, at the end of 2011, and we will. We are bound by that agreement and we will make good on it."

Some outside observers questioned the decision to stick so firmly to the 2011 deadline - and to describe the current moment as a watershed, given how slowly and unevenly Iraq has improved.

"I don't think moments of transformation are the right way of thinking about Iraq," Stephen Biddle of the Council on Foreign Relations said. "Everybody wants them. Both political leaders and analysts are looking for them as a way of organizing our thoughts about a long, complicated process. But the reality of the situation is Iraq had become an extremely violent ethnic conflict by mid-2006, not unlike the Balkans or Rwanda."

Obama has given just one other Oval Office speech, on the BP oil spill; that he is doing it there, rather than from a military base or the Rose Garden, illustrates the significance the White House attaches to the issue.

While he has aggravated liberals in other national security arenas, including his failure to close the prison facility at Guantanamo Bay and his escalation of the war in Afghanistan, Iraq is one relatively bright spot.

"The President and this administration are making good on our commitment to end the war in Iraq responsibly and to help build a stable, self-reliant, and sovereign Iraq," said Blinken. Biden, who made his his sixth trip to Iraq to participate in the "change of mission" ceremony, planned to give Iraqi leaders a preview of the president's speech, he said.

Ending combat in Iraq may help offset some concerns about Afghanistan, officials said. Even after deploying an additional 30,000 troops there - taking the total to nearly 100,000 - the reduction in Iraq means that about 30,000 fewer troops are serving "in harm's way" abroad, one administration official said. And the reduction frees up financial resources, including domestic funding for roads, bridges and schools - a point Obama will underscore. An official said that the president will describe the "kind of expenses we've been making in Iraq versus the kind of investments we will be making here at home."